Carb settings

[mrb]

Hi There !

Am a novice so asking advice before taking her into a garage ! Couldn't seem to get the idling speed right on my 1098 - had already checked oil in dash spot - etc - does run ok be it a little fast by removing air filter - so am l correct in thinking that l may need to adjust the jet at the bottom - where the taper pin fits ? can it be checked in situ or does the carb have to removed ? hope l've explained plainly ?

Regards Dave

[panky]

I would fit a new filter first of all, the air flow is so low at idle taking the filter off shouldn't affect the idle. To check the idle mixture first get the engine nice and warm then feel under the carb for the lift pin, it's a small spring loaded pin that lifts the carb slide up slightly, if the engine speeds up it's too lean, if it slows down it's too rich, no effect or very slight increase in engine speed is OK. Another easier way is to run the engine up to normal temperature then pull the choke out, but not to the point where the throttle stop is reached, again if the engine speeds up it's too lean if it slows down it's too rich.

[mrb]

Thanks very much will try that method tomorrow ! but have actually renewed air filter - it was just that a elder man up the street said he had a minor and it the bottom jet that get stuck ? but will do your test tomorrow thanks again

[panky]

I guess the jet could stick if the carb had been laying around for years but not had one seize up on a running car.

[bmcecosse]

It's quite the opposite - too rich and the engine will speed up, and too weak it will slow/stall when you lift the pin. And yes to adjust - you turn the jet nut a little bit at a time. If you don't have the workshop manual then download one FREE by searching on Google.

[mrb]

Thanks Bmc ! wasn't aware you could download a manual - not a good explanation in Haynes !

[panky]

Well I had a 50/50 chance of getting it right

[liammonty]

Just bear in mind that adjusting the bit that you have referred to will adjust the mixture (which will have a small effect on the idle speed) but that isn't the way to set the idle speed itself! That is done by turning the screw on the throttle linkage at the carb. Just check that you are turning the right one as there are two, and one is for setting the fast idle, i.e. the idle speed when the choke is out. If you do adjust the mixture nut, remember how many flats you have turned it so that you can put it back to how it was if it turns out that it isn't the mixture that is wrong!

[mrb]

Thanks again to you all ! followed your instructions and "spot on" filter now back in and running almost perfect ! just need really to go a good run and then re-adjust when warmer !


Thanks again for help


Dave

[bmcecosse]

The real test is indeed to go a good long run - switch off 'at speed' and glide to a halt (so no idling) and whip out a couple of plugs to see what colour they are. Should be a nice light beige biscuit colour - not white - or dark brown/black.